1. Field of the Invention
The present invention relates to a lithography apparatus using an immersion exposure apparatus, a method for forming a pattern and a method for manufacturing a semiconductor device.
2. Description of the Related Art
As a semiconductor manufacturing apparatus, a lithography apparatus is known. The lithography apparatus includes a resist processing apparatus, a transporting apparatus connected to the resist processing apparatus, and an exposure apparatus connected to the transporting apparatus. Transporting of a wafer between the resist processing apparatus and the exposure apparatus is performed through the transporting apparatus.
In a conventional lithography apparatus, temperature and humidity in a transporting apparatus are not controlled. Even though the temperature and the humidity are controlled, the temperature and the humidity in the transporting apparatus are controlled independently of the environment in the exposure apparatus.
A window for exchanging a wafer is formed between the exposure apparatus and the transporting apparatus. In the conventional lithography apparatus, air in the exposure apparatus flows into the transporting apparatus through the window.
The air flow does not pose any problem when a conventional dry exposure apparatus is used. However, the air flow poses a problem when an immersion exposure apparatus (Jpn. Pat. Appln. KOKAI Publication No. 10-340846) in which a high-humidity state is set near a wafer stage. That is, the temperature and the humidity in the exposure apparatus are difficult to keep constant, and the temperature of a wafer transferred into the exposure apparatus from the transporting apparatus disadvantageously varies. Hereby, dimensional controllability and alignment accuracy which are important in the lithography step are degraded, so that a designed resist pattern can be hardly formed.
Furthermore, when an immersion exposure apparatus is used, there is a case that moisture remains on a surface of wafer which the immersion exposure has finished, or moisture remains on a rear surface of the wafer by material educed from the resist film on a surface during the exposure (announcement from Nikon Corporation in an immersion exposure workshop: Nikon, hyperlink address is sematech.org/resources/litho/meetings/immersion/20040128/index.htm)). When the wafer in such a state is processed in the resist processing apparatus, contamination occurs in the resist processing apparatus.